High CPU on the monitored host caused by database agents (4226246)

When a Foglight database agent is enabled, monitored collections may lead to high CPU usage on the target database host. Disabling the agent typically results in CPU activity returning to normal levels.

This behavior is more noticeable on database instances with low or no workload. For example, SQL Performance Investigator (SQL PI) collections run every second (1000 ms) by default, which may appear resource-intensive on underutilized systems. On actively used instances, the impact is generally negligible.

Several conditions may contribute to increased CPU usage during Foglight monitoring:

1. Deadlock collection via Extended Events in SQL Server.

2. SQL PI environment sizing or antivirus exclusions are not correctly configured.

3. SQL PI get_active_waits query on SQL Server instances.

4. Interrupted sessions due to firewall issues causing session leaks.

5. Intermittent connectivity issues to Oracle hosts.

6. Outdated database maintenance (e.g., missing index/statistics updates).

7. Underlying disk I/O performance issues.

8. Resource contention from memory pressure or competing applications.

9. SQL Server Error Log collection via DCOM (OS method).

• Resolution 1 (Most Common - SQL Server):
  Refer to KB 4228897 for guidance on changing the Deadlock collection method from Extended Events to Trace.
• Resolution 2:
  Review the Foglight for Databases Deployment Guide to ensure proper sizing and environment requirements for SQL PI are met.
• Resolution 3:
  See KB 4226229 for instructions on reducing SQL PI collection workload on SQL Server hosts.
• Resolution 4:
  For details on session issues caused by firewall interference, refer to KB 4295218.
• Resolution 5 (Oracle):
  Connectivity issues to Oracle hosts are also covered in KB 4295218.
• Resolution 6:
  Ensure regular database maintenance is performed, including index optimization and updating statistics.
• Resolution 7:
  Investigate disk I/O performance and physical datafile locations for potential bottlenecks.
• Resolution 8:
  Assess instance memory configuration. Ensure sufficient memory is available for the OS and other applications, including third-party monitoring tools that may be running alongside Foglight.
• Resolution 9:
  Change the SQL Server Error Log collection method from OS or FALLBACK to JDBC as documented in KB 4302796.